The effects of oral taurine administration on behavior and hippocampal signal transduction in rats

Taurine, 2-aminoethylsulfonic acid, is one of the most abundant amino acids in the brain. It has various important physiological functions as a neuromodulator and antioxidant. Taurine is expected to be involved in depression; however, knowledge regarding its function in relation to depression is limited. In this study, we attempted to elucidate the effects of oral taurine administration on antidepressant-like behaviors in rats and depression-related signal transduction in the hippocampus. In behavioral tests, rats fed a high taurine (HT: 45.0 mmol/kg taurine) diet for 4 weeks (HT4w) showed decreased immobility in the forced swim test (FS) compared to controls. However, rats fed a low taurine (LT: 22.5 mmol/kg taurine) diet for 4 weeks or an HT diet for 2 weeks (HT2w) did not show a significant difference in FS compared to controls. In biochemical analyses, the expression of glutamic acid decarboxylase (GAD) 65 and GAD67 in the hippocampus was not affected by taurine administration. However, the phosphorylation levels of extracellular signal-regulated kinase1/2 (ERK1/2), protein kinase B (Akt), glycogen synthase kinase3 beta (GSK3β) and cAMP response element-binding protein (CREB) were increased in the hippocampus of HT4w and HT2w rats. Phospho-calcium/calmodulin-dependent protein kinase II (CaMKII) was increased in the hippocampus of HT4w rats only. Moreover, no significant changes in these molecules were observed in the hippocampus of rats fed an HT diet for 1 day. In conclusion, our findings suggest that taurine has an antidepressant-like effect and an ability to change depression-related signaling cascades in the hippocampus.     

Effect of prolactin and bromocriptine administration on testicular metabolism in albino rats

Prolactin (PRL) and bromocriptine were administered subcutaneously to adult male albino rats and their effects on testicular metabolism have been analysed. PRL enhanced the activities of testicular androgen-dependent enzymes. In contrast, bromocriptine inhibited these enzyme activities, which was correlated to the blocking of PRL release by this agent. Hence, direct participation of PRL on the testicular function was evident.     

牛磺酸对脑创伤大鼠的脑保护作用

目的:探讨牛磺酸(Tau)预处理对弥漫性脑创伤(TBI)大鼠脑皮层超氧化物歧化酶(SOD)活力、丙二醛(MDA)含量、脑含水量(BWC)和脑皮层水孔通道蛋白4(AQP4)表达的影响。方法:复制大鼠TBI模型,分为假手术组(S组)、TBI组(T组)、低剂量Tau组(L组)和高剂量Tau组(H组),用比色法测定脑皮层匀浆液中SOD活力和MDA含量;干/湿法测定BWC;免疫组织化学检测脑皮层AQP4的表达。结果:T组大鼠脑皮层SOD活力显著低于S组,T组MDA含量、BWC和脑皮层AQP4的表达显著高于S组;H、L组脑皮层SOD活力显著高于T组,H、L组MDA含量、BWC和脑皮层AQP4的表达显著低于T组;H、L组之间差异无显著性。结论:Tau可能通过清除TBI后产生的的氧自由基、下调TBI大鼠脑皮层AQP4的表达减轻脑水肿,发挥其脑保护作用。     

Effects of taurine in glucose and taurine administration

Summary. Taurine has several biological processes such as hypoglycemic action, antioxidation, detoxification, etc. To assess the effect of taurine administration on the guinea pigs with hyperglycemia, blood glucose, C-peptide levels together with morphologic alterations in the pancreatic ultrastructure were investigated in terms of hypoglycemic action and malondialdehyde and total sulfhydryl group levels with regard to oxidation-antioxidation relation. Animals were divided into four groups of six. Glucose supplementation group was administrated a single dose of glucose (400mg/kg, i.p.) injection. Glucose and taurine supplementation group was administrated glucose treatment (a single dose, 400mg/kg, i.p.) following taurine (a single dose, 200mg/kg, i.p.). Taurine and glucose supplementation group was administered taurine treatment (a single dose, 200mg/kg, i.p.) following glucose treatment (a single dose, 400mg/kg, i.p.). Control animals received no treatment. Blood samples were collected at the end of the experiments for the determination of glucose, C-peptide (indicator of insulin secretion), lipid peroxidation (thiobarbituric acid reactive substances), and total sulfhydryl groups levels. Pancreatic tissue samples were then collected and processed for transmission electron microscopy. The findings showed that glucose supplementation following taurine administration significantly decreased blood glucose level by increasing C-peptide level and the pancreatic secretion stimulated morphologically and insignificantly changed thiobarbituric acid reactive substances and total sulfhydryl group levels. These observations suggest that taurine administration may be useful in hyperglycemia because of its hypoglycemic and protective effects.     

Histopathological and biochemical changes of morphine sulphate administration on the cerebellum of albino rats

In this study the long-term effects of morphine sulphate treatment (MST) on histopathological and biochemical changes in the cerebellum was assessed in albino rats. Normal saline (5 ml) was given orally as placebo in the control group (n = 25). Morphine groups received morphine orally at a dose level of 5 mg/kg body weight day after day for 10, 20 and 30 days (n = 25/group). Light microscopy revealed that the molecular layer showed vacuolation. The Purkinje cells lost their specific shaped appearance, decreased in size and numbers. The granular cells highly degenerated. Electron microscopy revealed fragmentation of the cisterns of the both types of endoplasmic reticulum, resulted in a progressive depletion of total protein contents as well as general carbohydrates in all treated groups as supported by histochemical observation. Obvious destruction of mitochondrial inner membrane and cristae mediate cell death. Also, abnormal nucleus with deformed perforated nuclear membrane and deformation of the plasma membrane with degeneration of the synapses could interpreted as a sign of necrosis. Biochemical analysis revealed that dopamine (DA) and norepinephrine (NE) were significantly decreased in four brain areas (cortex striatum, thalamus/hypothalamus, and cerebellum). In contrast, serotonin (5-HT) level was increased in these brain regions; with an exception of 5-HT on day 10 and neurotransmitter levels in the pons were unaffected. The quantitative analysis showed a significant decrease (P < 0.05) in the diameter of Purkinje cells and in the thickness of both molecular and granular layers treated groups. Morphine sulphate induces may be a cell death or necrosis in the rat cerebellum and modulating neurotransmitter system. Our findings pointed out the risk of increased cerebellum damage due to long-term of morphine use.     

A study on the potential reprotoxic effects of thimerosal in male albino rats

Thimerosal is ethyl mercury based compound which is being used as a preservative in vaccines since decades. Pharmaceutical products and vaccines that contain thimerosal are among the potential source of mercury exposure. Current research was intended to ascertain the reprotoxic effects of thimerosal on rat testes. Twenty-four adult male albino rats were sorted into four groups (n = 6). The first group was a control group. Rats of experimental Group 2, 3 and 4 were treated with various dosages of thimerosal (0.5, 10, 50 mg/kg) respectively. Rats were decapitated after thirty days of trial and different parameters were analyzed. Thimerosal exposure resulted in a significant decrease in antioxidant enzyme activities including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione reductase (GSR) and increased levels of thiobarbituric acid reactive substances (TBARS). Different doses of thimerosal significantly decreased (p < 0.05) the concentration of plasma testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH). Additionally, Daily sperm production (DSP) and efficiency of daily sperm production were significantly reduced followed by thimerosal exposure. Moreover, thimerosal significantly (p < 0.05) decreased the primary spermatocytes, secondary spermatocytes, number of spermatogonia along with spermatids. Thimerosal induced adverse histopathological and morphological changes in testicular tissues such as decreased Leydig cells, diameter of seminiferous tubules, tunica albuginea height and epithelial height. On the other hand, the increase in tubular lumen and interstitial spaces was observed due to thimerosal. These outcomes indicated that thimerosal has potential reprotoxic effects in male albino rats.     

Potential role of kinins in the effects of taurine in high-fructose-fed rats

The present work investigates the involvement of kinins in the effects of taurine in fructose-fed hypertensive rats. The effects of taurine on blood pressure, plasma glucose, insulin, and the insulin sensitivity index were determined. Angiotensin-converting enzyme (ACE) activity and nitrite content in plasma, plasma and tissue kallikrein activity, and taurine content were also investigated. The blood pressure changes in response to the coadministration of inhibitors of the synthesis of nitric oxide (NO), prostaglandins (PGs), or a kinin receptor blocker along with taurine was also evaluated. Fructose-fed rats had higher blood pressure and elevated plasma levels of glucose and insulin. Kallikrein activity, taurine, and nitrite contents were significantly lower in fructose-fed rats as compared with controls. The increases in systolic blood pressure, hyperglycemia, and hyperinsulinemia were controlled by taurine administration in fructose-fed rats. ACE activity was lower, while nitrite and taurine content and kallikrein activity were higher, in taurine-supplemented rats as compared with fructose-fed rats. A significant increase in blood pressure was observed in rats cotreated with the inhibitors Hoe 140 (a kinin receptor blocker), L-NAME (a NO synthase inhibitor), or indomethacin (a PG synthesis inhibitor) with taurine for 1 week as compared with taurine-treated fructose-fed rats. This suggests that the antihypertensive effect of taurine in fructose-fed rats was blocked by the inhibitors. Augmented kallikrein activity and, hence, increased kinin availability may be implicated in the effects of taurine in fructose-fed hypertensive rats.     

The effects of adrenalectomy on the harderian gland of the Wistar albino rats

Harderian glands of the Wistar albino rats normal and adrenalectomized were investigated by light microscopy. In normal, these glands have a tubuloalveolar structure. The gland is located in the medio posterior aspect of the orbit. It is lobulated and appears homogeneous in colour and texture. Harderian gland consist of tubules with wide lumina lined by a single layer of columnar epithelial cells surrounded by myoepithelial cells within their basal lamina. It contains porphyrin pigment which is stored as solid intraluminal deposits. The glandular epithelium possesses two cell types, termed A and B. Type A cells are more numerous. The single excretory duct of the gland is directly continuous with endpieces at the hilus and opens nasally and ventrally to the third eyelid. The excretory duct is accompanied by many acini of small serous glands around it. The tubuloalveoli of the gland is not divided into lobules. There is no branched duct system within the gland. The secretion seems to be associated with porphyrins, is essentially released by exocytosis, but holocrine secretion also occurs. The single excretory duct is lined by a stratified epithelium. The gland is surrounded by a collagenous capsule. The adrenalectomy, caused degenerative changes in the glands. Epithelial height was lower than in normal gland epithelium. Most of the acini were completely disorganised. The acinar lumina were filled with porphyrin debris. The results suggest that rat harderian glands are sensitive to adrenal androgen changes in both male and female rats.     

Supplemental taurine in diabetic rats: effects on plasma glucose and triglycerides

The present study has indicated that significant shifts in plasma, urinary, and tissue taurine and in non-taurine dialyzable amines occur in the STZ-induced diabetic rat, especially in the kidney. Taurine administration at relatively low dosage ameliorated only kidney taurine concentration. Anticipated alterations in plasma glucose and creatinine were observed but neither of these changes was affected by taurine administration. Similarly, urinary output of creatinine, glucose, and NAG increased significantly among diabetic rats, but none of these were detectably influenced by taurine. Increases in plasma triglycerides observed in STZ-induced diabetes appear to be attenuated by taurine administration, and although cholesterol concentrations were lower in taurine-treated rats, the differences were not statistically significant. These findings should encourage further studies of these effects in rats as a useful model for several complications of human diabetes including atherosclerosis, retinopathy, and nephropathy.